Rock bolts, which are made from elongate tubular shanks, are used in many applications, particularly in underground mining. In hard rock mining e.g. in gold and platinum mines in South Africa, it is often difficult to drill a borehole of reduced dimensions into a rock body. This means, in turn, that when a rock bolt is to be fixed in a borehole using grout or resin, the rock bolt must have a predetermined maximum diameter, relative to the diameter of the borehole, to ensure that the resin or grout bonding process is effectively implemented.
To allow for the rock bolt shank to have a desirable outer diameter, without using an excessive amount of material, use is made of a tubular shank. Typically one end of the shank projects from a mouth of the borehole adjacent a rock face. According to requirements, the protruding end of the shank may be threaded so that a nut can be coupled thereto. This is to allow a tensile force to be placed on the shank. A problem with this approach is that, in forming the thread, the strength of the shank is reduced.
An object of the present invention is to provide a rock bolt which, at least in one preferred embodiment, addresses the aforementioned factor.